Expansion-bit



A. B. STGNE.

EXPANSIQN BIT.

(No Model.)

No. 560,050. PatentdMay 12, 1896.

.i-V L @5% AN DREW RGRAHAMJNUTOUTHQWASNI NGION, D C

` NrTn STATES i ATENT Gratien.

ARTHUR B. STOXE, OF IVINDSOR, CONNECTICUT.

EXPANSlON-BIT.

SPECIFICATION forming part of Letters Patent No. 560,050, dated May 12,1896.

Application filed January 30, 1896. Serial No. 577,394, (No model.)

To @ZZ whom, it may concern:

Be it known that I, ARTHUR B. STONE, a citizen of the United States,residing at Vindsor, in the county of Hartford and State of Connecticut,have invented certa-in new and useful Improvements in Expansion-Bits, ofwhich the following is a specication.

My invention relates to improvements in expansion-bits; and the chiefobjects of my improvements are to dispense with the use of ascrew-driver in adjusting the bit and to positively secure the extensionarm or cutter against slipping. y

In the accompanying drawings, Figure li a sectional front elevation ofthe main portion of my bit, the shank portion beingbroken off. Fig. 2 isa side elevation of the same, and Fig. 3 is a section elevation showinga modification thereof.

The bit-head A is or may be of any ordinary form for this class of bitsan'd is provided with a transverse groove or recess, in which theextension arm or cutter B is guided and held. I prefer to make part ofthe front edge of the extension-arm of a beveled form and to form anoverhanging wall at the corresponding side of the recess, so as to fitsaid bevel, as in ordinary bits of this class. IVhat I call the frontedge of the extension-arm is that edge which is nearest the cutting endof the bit. The rear edge of the extension-arm is toothed, as shown, toform a rack 4:. The head B in addition to being grooved transversely toreceive the extension-arm is slotted through longitudinally in rear ofsaid arm to receive the pinion 5, which is held in place by the walls oneach side of the slot and by a pin or screw 6, extended through the lip7, the pinion and into the body of the head opposite said lip 7. Thislip preferably should extend forward partially over the broad side ofthe extension-arm, as shown in Fig. 2. I prefer that the edge of thepinion 'shall project slightly at each side of the head for convenienceof manipulation.

Upon the head, in the rear of the pinion, is a sleeve S, and in rear ofsaid sleeve there is a nut 9, screwed upon a threaded portion of thehead or body of the bit. The exterior of the nut should be knul-led, asin other nuts for analogous uses, and the pinion should be somewhatloosely pivoted.

By loosening the nut and withdrawing the front end of the sleeve fromits engagement with the teeth of the pinion the said pinion may beturned by ones lingers and thereby move the extension-arm either waythrough the engagement of the teeth of said pinion with the rack.Although the pinion is loosely pivoted, it is still coniined closelyenough to hold the teeth of the pinion and rack in engagement for movingthe eXtensionarm. IVhen said extension-arm has been adjusted to thedesired position, the nut 9 is turned to force the sleeve forwardlyagainst the pinion and into engagement with the teeth thereof at theopposite sides of said pinion, as shown in Fig. l. The same act willalso force the pinion firmly against the rack at the rear edge of theextension-arm and press the front edge of said arm iirmly to its bearingin the head, whereby the said pinion is firmly clamped between theextension-arm and the sleeve. The engagement of the sleeve with theteeth of the pinion and the pinion with the rack, in addition to saidclamping function, will form a positive lock for preventing theeXtension-arm from moving endwise, so that the boring of a hole ofuniform diameter from end to end is always insured. The pinion issomewhat loosely pivoted, so as to permit the pressure of the nut andsleeve being thrown upon the edge of the extension-arm.

The modification shown in Fig. 3 differs from that shown in Figs. l and2 by the substitution of the two pinions 5L and 5b for the single pinion5, and they are the equivalent therefor to a large extent and are thefull equivalent thereof, excepting as they are more expensive to buildand not quite so convenient to manipulate. The locking devices hereinshown-viz., the nut and sleeve for engaging the teeth of the pinion andforming a positive lock for the eXtension-arm-are considered the bestdevices for that purpose now known to me; but I do not wish to limitmyself to the details of construction shown and described, as I claimthe right to make such mechanical changes and variations as may fairlyfall within the spirit and scope of my invention. As in otherextension-bits, arms of different lengths may be employed, and a scaleand index may also be used to indicate the size that the bit will bore;but I IOO consider it unnecessary to show and describe these Well-knownfeatures.

I claim as my inventionl. The combination of the bit-head, theextension-arm properly guided therein and having a rearwardly-facingrack, a pinion with its teeth in engagement with said rack, and lockingdevices or acting directly upon the teeth of said pinion and positivelylocking it in place and through said pinion positively looking said armin its position in said head, substantially as described.

2. The combination of the bit-head, the extension-arm properly guidedtherein and havinga rearwardly-facing rack, a pinion pivo ted in thehead opposite the rack of the Said ex- ARTHUR B. STONE.

lVitnesses: LEROY M. GoWLEs, GEORGE W. KLETT.

